Less than one year after Michigan State University added a commercial-sized anaerobic digester to its campus sustainability arsenal, the magic of bioengineering has transformed thousands of tons of organic waste from MSU and the greater Lansing area into biogas that has generated more than 1.7 million kWh of electricity.

The “magic of bioengineering” used by the South Campus Anaerobic Digester is actually a natural decomposition process known as anaerobic digestion, which converts organic materials (dairy manure from the MSU Dairy Teaching and Research Center, food waste from several campus dining halls, fruit and vegetable waste from the Meijer Distribution Center in Lansing, and fats, oil and grease from local restaurants) into biogas. Methane and carbon dioxide are the primary gaseous components of biogas, which then can be burned to generate electricity and heat (steam), or purified and compressed for use as natural gas.

However, the power of anaerobic digestion technology extends well beyond its ability to produce energy. It treats organic waste, such as animal manure, in an environmentally friendly way, reducing odors, greenhouse gas emissions, pathogens and water pollution potential.

The anaerobic process also produces a slurry called “digestate,” a valuable – and organic – fertilizer that contains almost all of the nutrients essential for plant growth (phosphorus, potassium, nitrogen) and can be spread on fields and gardens. This saves the cost and the energy that would have been spent producing artificial fertilizers. And, since the biogas has largely been removed from this fertilizer, it does not smell – unlike the conventional animal waste products used as fertilizers.

The operation itself is simple: food waste and other organic matter are placed in an airtight tank, which holds about 450,000 gallons of material. The tank contents are maintained at roughly 100 degrees Fahrenheit for 20 to 30 days. During that time, the organic material is decomposed by a group of naturally occurring microorganisms found in livestock manure. The result is biogas and a slurry of partially decomposed organic matter, water and nutrients.

“The idea that certain microorganisms will flourish in an oxygen-deprived (anaerobic) environment and then break down organic materials to produce methane has been well known since the 1700s,” says Wolfgang Bauer, University Distinguished Professor of Physics and Astronomy and champion of MSU’s alternative energy initiatives in his role as senior consultant to MSU’s executive vice president of Administrative Services, Satish Udpa. “What is relatively new about this is that years of research – including at MSU’s six-year-old Anaerobic Digester Research and Education Center (ADREC) http://www.egr.msu.edu/bae/adrec/  – have made this process much more economically viable.”

More than 15 faculty members from the MSU colleges of engineering, natural science, and agriculture and natural resources are involved in research at MSU’s Anaerobic Digester Research and Education Center, which is located near the South Campus Anaerobic Digester.

Using the extensive lab and pilot facilities in the center – including several different sizes of anaerobic digesters – MSU researchers are studying how to:

• optimize microbial communities by identifying and selecting new microbes for biofuel/chemical production;
• create a self-sustained system to reclaim potable water from agricultural/municipal wastewater;
• develop a new anaerobic digestion system for simultaneous production of transportation fuel and reclaimed water;
• find value-added chemicals that can be produced from organic wastes; and
• devise processes for integrated farm-based biorefining.

As part of MSU’s alternative energy initiative, MSU scientists are collaborating with engineers and scientists from Ohio State University, Washington University in St. Louis, and USDA ARS on algae and transgenic microbe projects to convert organic residues into polymers and advanced fuels. They also are working with companies across the U.S. on organic waste utilization.

“The goal of the Anaerobic Digester Research and Education Center is to develop off-the-shelf anaerobic digestion technology so it becomes cost effective for small- to medium-size farms,” explains Bauer. “There are more than 2,500 dairy farms in Michigan that fall in this range (200-500 milking cows). The potential of anaerobic digestion technology in converting animal manure to energy, while at the same time reducing greenhouse gas emissions, is huge.”

The same need for environmentally friendly waste-to-energy solutions has become critical in South and Central America, where MSU is leading a multidisciplinary and multinational research team (Costa Rica, Nicaragua, Panama). Last year, working with the University of Costa Rica, MSU researchers brought an innovative solar-powered anaerobic digester online that is similar to MSU’s South Campus Anaerobic Digester. Today it is providing power to the Fabio Baudrit Agricultural Experiment Station in Alajuela, Costa Rica.

Other international projects include MSU’s collaborations with the:

• University of Sao Paulo in Brazil, on ways to convert municipal waste and “bagasse,” the by-product of making bio-ethanol from sugarcane, into energy via anaerobic digestion;
• Yunnan Academy of Scientific and Technical Information (YASTI) in Kunming, China, on biogas development and technical training in Asia and southeast Asia; and
• DQY Agriculture Co. (the largest egg producer in Asia) to develop a wastewater treatment system to reclaim the water from anaerobic digestion effluent.

“Instead of waste being an environmental burden, it can be a very valuable asset,” says Bauer. “While anaerobic digestion is just one of the solutions we are working on, it offers great promise for helping supply our future energy needs.”

For more information about Michigan State University’s Anaerobic Digestion Research and Education Center, contact Dana M. Kirk, Ph.D., P.E., assistant professor and manager, (517) 432-6530 or kirkdana@msu.edu.